von Willebrand Disease (VWD) Testing Interpretations
This assay is designed to distinguish type 2N von Willebrand disease (an autosomal recessive disorder) from mild hemophilia A and hemophilia A carriers. Patient VWF is captured with monoclonal antibody in a microtiter well, any patient-derived FVIII:C is washed away and recombinant FVIII is then added. Patient-derived VWF antigen is quantitated immunologically, the bound FVIII is quantitated by chromogenic assay, and assay results are reported as the ratio of FVIII to VWF. Comparison is made to the results obtained with well-defined control plasmas (either compound type 1/type 2N VWD, 2N carrier state or normal). Numerical results and an interpretation are provided.
A ratio near 1.0 is observed for normal samples, vary low ratios are observed for samples obtained from patients with type 2N VWD. Intermediate ratios are observed for heterozygous carriers of type 2N VWD.